1. Technical Field
The exemplary and non-limiting embodiments relate generally to noise removal and, more particularly, to removing noise generated from an internal non-audio component in an apparatus from a signal.
2. Brief Description of Prior Developments
Non-audio components in mobile devices increasingly have features that cause noise. For example, a mobile device may have a camera which produces noise if features such as AutoFocus (AF) and Optical Image Stabilization (OIS) are used. Because mobile devices are small in size, the noise is easily picked up by the air microphone(s) of the mobile device. This may cause problems to video sound tracks for example.
Removing camera noise from audio tracks is a significant problem. Camera companies go as far as introducing new lens generations (e.g. CANON with STM lenses) for more silent operation, but with AF motors which are not as good as previous AF motors.
Removing camera noise from audio tracks can, to some extent, be done by measuring the noise signal caused by the camera to the air microphones and then subtracting the measured signal from the microphone signal when the camera is operational. Within the scope of mobile devices, current noise removal systems typically have a single constant model of the noise, and they apply noise removal when the system “guesses” camera noise to be present. However, variability of the noise over time, component wear, different calibration between microphones, devices and camera components, and changes in the noise when the device is held differently cause the noise to be difficult to estimate without real-time measurements. Thus, a static single constant model for noise reduction of noise generated from an internal non-audio component can be improved upon.